Amalgam is an alloy of mercury and another metal. Such amalgam has electrode activities of mercury and can be formed into a solid phase. Thus, studies for utilizing the amalgam as an electrode material have been conducted. Generally, silver amalgam has been utilized in many cases. Recently, there has been reported a case where dental amalgam is applied to electrochemical reduction of carbon dioxide. In all of these cases, when an amalgam electrode is manufactured, a method (amalgam-setting reaction) of mixing metal powder with mercury into the dough at a high speed with an amalgamator and then putting and solidifying the dough in a mold having a predetermined shape is used. Particularly, dental amalgam is prepared by mixing mercury with amalgam powder, and amalgam powder is classified into low-copper amalgam and high-copper amalgam depending on the content of copper (Cu). For example, amalgam powder ANA 2000 produced by Nordiska contains Ag, Sn, and Cu in the amounts of 43.1 wt %, 30.8 wt %, and 26.1 wt %, respectively. Dental amalgam is prepared by mixing well the amalgam powder of 55 wt % and liquid mercury of 45 wt %. In this case, the final composition contains Hg (45 wt %), Ag (24 wt %), Sn (17 wt %), and Cu (14 wt %). The method for manufacturing an amalgam electrode by mixing and then solidifying as described above (see Korean Patent No. 1324742) has a problem that it cannot be applied to manufacturing an electrode by forming amalgam on surfaces of electrodes having various shapes, for example, a surface of a porous electrode.